JPS6091239A - Detecting system of printing density - Google Patents

Abstract

PURPOSE:To detect the density highly accurately step by step by one measurement, by changing a black and white judging reference in correspondence with the optical brightness, which is measured with respect to a medium. CONSTITUTION:The light of a lamp 101, which is reflected by a medium 102 that detects the density of printing, is converted into an electric signal by an optical sensor 104 through a lens system 103. The signal is sent to a black and white judging reference generating part 106 and a density judging part 107 through an amplifier part 105. An output 301 of the amplifier part 105 is compared with an output 302 of the generating part 106 in the judging part 107. At this time, the output 302 is set so that it is changed with the output 301. When the density on the medium 102 is larger than the output 302, white is determined. When the density is smaller, black is determined. By the adequate setting of the output 301, the density of the printing and the like on the medium 102 can be detected highly accurately step by step.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to optical density detection, and particularly to a method suitable for detecting the density of printed characters.

[Background of the invention]

In the conventional optical density detection method using digital quantity display, it is possible to determine whether a specific density is dark or light.

Since it can only judge values, it has the disadvantage that in order to detect dark and light levels in stages, it is necessary to change the criteria and perform measurements several times.

[Purpose of the invention]

An object of the present invention is to provide a method for optically detecting print density, which detects the density in stages in a single measurement.

[Summary of the invention]

In printing, the electrical signal waveform when measuring optical brightness differs depending on the density of the ink and printing ribbon used even for the same printing. , the depth of the valley that falls into the printed area depends on the density of the ink and printing ribbon, and is deeper when it is thicker and shallower when it is thinner, so it is possible to measure the depth of this valley relatively and easily detect the print density. It is something to do.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

In the print density detection device implementing the present invention, light is used.

Light from a lamp 101 serving as a source illuminates a medium 102 for detecting print density, a lens system 103 collects reflected light from the medium, and an optical sensor 104 converts the intensity of this light into an electrical signal. The electrical signal is sent to the amplification section 105, and its output is sent to the black and white judgment standard generation section 106 and the density judgment section 1.
07, and in this concentration determination section 107, the amplification section 10
5 and the output from the black-and-white determination standard generating section 106 are compared to determine the print density on the medium.

Next, the black and white judgment standard generation section 106 and the density judgment section 107
The details will be explained with reference to FIGS. 2 and 3.

FIG. 2 is an enlarged view of the medium 102 in FIG. The power of the amplifying unit 501 shown in the figure is as shown in the figure. Central part 305
reads the text and indicates that the electrical signal is decreasing.

At this time, the output 602 of the black and white determination criterion generator is set to change according to the power of the amplifier 301 .

Furthermore, the central portion 305 shows waveform changes associated with character reading. Now, assuming that the print density on the medium is light, the central part of the amplifying part power changes upward as shown at 304, and the change from the white background becomes smaller, but the power for the black and white judgment reference part changes upward. Since it is set to change gradually in response to a change in the direction, it becomes as shown in 306. The density determination unit 107 compares both the output of the amplification unit and the output of the black-and-white determination reference generation unit, and if the output of the amplification unit 105 is larger than the output of the black-and-white determination reference generation unit 106, it is determined to be white, and if it is smaller, it is determined to be black. However, when comparing the lengths determined to be black, when the characters are dark, the width of the characters is determined to be black, as shown in 507, whereas when the characters are light, the length is determined to be black, as shown in 308, K, which is shorter than the width of the characters. It is judged as narrow and black. The density determination unit 107 measures how much of the entire sensor reading line 202 is determined to be black, and compares the result with the result when reading a sample printed with accurate density. In particular, it is possible to detect the print density of characters on the medium.

Next K, black and white judgment standard generation section 1o6 and density judgment section 107
The circuit configuration is shown in Figure 4.5, and the details of the determination method will be described accordingly.

The output of the amplification section 105 is further amplified at 401 and output to CB,
The output is sent to a charging/discharging circuit 402, and due to 402, the black and white judgment reference output changes slowly with a time constant according to the value of CR in response to changes in the power of the amplifier section.

Note that 403 and 404 Fi are circuits that limit the upper and lower limits of the black and white determination reference output. The output of 402 is
A comparator 501 compares the output with the output of the nine amplifying section 105 and converts it into a black and white binary digital signal.

This digital signal is sent to 502, sampled at regular clock intervals, converted into 8-bit unit data, and sent to a processing section 503 having a microcomputer. This 50
In step 3, count the number of black and white bits sent from 502,
The printed character density is determined by comparing it with the number of bits for each density previously stored in the memory. In order to actually improve the law determination accuracy, one character is divided into 18 equal parts from the top to the bottom of the character, and the density is determined by the total number of measurements in each part. If you specify the characters and 7 onts, 1
The area ratio of the character portion to the white background within the eight measurement ranges is constant, and the measurement accuracy is dramatically improved.

As described above, the present invention has the effect of being able to determine the density of characters printed on a print medium.

〔Effect of the invention〕

According to the present invention, the density on the medium can be detected at the same time as the senna is read, and the output result can be grasped as a digital quantity, which has the effect of enabling highly accurate density detection at low cost.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention, FIG. 2 is a partially enlarged view of FIG. 1, FIG. 6 is a schematic diagram of the electrical signal in FIG. 1, and FIG.
FIG. 5 is a detailed view of a portion of FIG. 1. 106... Black and white judgment standard generation section, 107...
...concentration determination section,

Claims (1)

[Claims] 1. In an optical measuring device, which consists of a part that measures the optical brightness of the medium, a reference generation part for determining brightness as black and white, and a part that compares and determines the brightness measurement results with the black and white determination standard, A print density detection method characterized by changing the judgment standard according to the measured optical brightness.